Cylinder head



April 9, 1940. TJAARDA 2,196,370

CYLINDER HEAD Filed Sept. 10, 1957 I INVENTOR M, (Mum,

A" whamm- PATENT OFFICE CYLINDER HEAD John 'ljaarda, Birmingham, Mich., assignor to Briggs Manufacturing Company, Detroit, Mich., corporation of Michigan Application September 10, 1937, Serial No. 163,282

8 Claims.

' This invention relates to cylinder heads for internal combustion engines and particularly, al-

, though not exclusively, to a composite head made of a cast base plate and a pressed sheet metal cover forming a water jacket. The invention in one of its aspects also comprises an improved method of manufacturing such composite cylinder head.

It is commonly appreciatedin the art that nulU merous advantages may be obtained if cylinder heads for internal combustion engines are not made as cast units but are built up of a cast base plate and a pressed sheet metal cover secured together to provide the necessary space for circulation of the cooling water. However, great difiiculties have heretofore been encountered in providing a cylinder head of the above character which would not leak in places of juncture of the base plate and the sheet metal cover, and

particularly in junctures thereof at the spark plug nests. Said difilculties have resulted primarily from the fact that it is impractical or exceedingly difficult to secure a pressed metal jacket to a cast base plate by welding. Welding together a sheet metal cover and a cast base plate ordinarily made of different metals involves many technical difllculties, and ordinarily no lasting water tight joint can be produced in such cases by welding. Such dimculties are particularly go hard to overcome when a cast aluminum base plate and a pressed steel cover are used. While at the places where studs pierce'through the cylinder head the required tightness of the joints may be attained by the pressure of the nuts on the pressed steel cover supported around the studs by suitable bosses, the spark plugs cannot be called upon to exert a sufllciently high pressure onthe cover and, therefore, some other means should be provided at the spark plug nests 40 to insure the necessary tightness of the joints thereat. Attempts to effect tightness of the joints by soldering or by sealing the same with the aid of plastic materials have proved ineffective because of the inability of such seals to resist strains imposed on such joints by vibrations of the cover due to the operation of the engine and by the hydraulic pressure caused by pulsations of the ,fluid within the jacket.

One of the objects of the present invention is to overcome the foregoing difllculties and to provide an improved composite cylinder head having water tight joints at the spark plug nests.

Another object of the invention is to provide an improved composite cylinder head which is very to l ht and which does not leak at its seams.

A further object of the invention is to provide a composite cylinder head made of a cast aluminum base plate and a pressed steel cover in which water tight joints are effected at the places of juncture of the aluminum plate and steel cover. I

A still further object of the invention is to provide a cylinder head of the foregoing character in which operative vibrations of the cover do not afiect the seams thereof.

A still further object of the invention is to 10 provide an improved method of fabricating a composite cylinder head made of a cast aluminum base plate and a pressed steel cover.

It is an additional object of the present invention to provide a composite cylinder head of 15 the foregoing character which is simple in construction and is relatively inexpensive to manufacture.

Other objects of this invention will appear in the following description and appended claims, Q reference being had to the accompanying drawing forming a part of this specification wherein like reference characters designate corresponding parts in the several views.

Fig. l is a top view of an engine provided with 35 a cylinder head embodying the present invention.

Fig. 2 is a fragmentary sectional view, looking in the direction of the arrows, the section being taken on the broken line 2-2 of Fig. 1.

Fig. 3 is a view similar in part to Fig. 2, said 30 view showing the cylinder head on an enlarged scale and illustrating the method of welding the flanges thereof.

Before explaining in detail the present invention it is to be understood that the invention is 35 not limited in its application to the details of construction and arrangement of parts illustrated in the accompanying drawing, since the invention is capable of other embodiments and of being practiced or carried out in various ways. Also it is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation, and it is not intended to limit the invention claimed hereinbeyond the requirements of the prior art.

In the drawing there is shown, by way of example, the upper portion of a cylinder of an internal combustion engine with a detachable composite cylinder head constructed in accordance with one embodiment of the present invention. 50

Referring more particularly to the drawing, the numeral It represents a cylinder block of a conventional internal combustion engine having a cylinder II and a piston l2 reciprocable therein. The numeral 13 indicates a poppet valve fitted into a seat I4, the valve intended to control the intake of the engine. A composite cylinder head, indicated generally by the numeral I5, is secured to said cylinder block In, a gasket l6 being interposed between the head and the cylinder block. The head l5 comprises generally a cast aluminum base plate |1 shaped to provide a combustion chamber I8 and flanges I9 and 28 engaging the milled top surface of the cylinder block. On said plate |1 there are integrally formed a number of stud bosses 2| having drilled holes for the passage of studs 22, and a number of spark plug bosses 23, each of them adapted to receive a spark plug 24 held in a tapped hole 25 and partially surrounded by a tapering counterbore 26. A gasket 24a is interposed between the spark plug 24 and the plate IT in order to insure tightness of the joint. The base plate I1 is preferably cast with an insert of sheet metal, preferably sheet steel, forming a peripheral flange 21 which extends outwardly and beyond and continuously around the periphery of the base plate I1.

A pressed cover 28, made preferably of sheet steel, is secured to said plate |1, said cover being suitably shaped to provide the water space 29. A depending surrounding flange extends continuously around said cover and is provided with an outwardly extending flange 3| adapted to engage the flange 21 embedded in the plate I1, said flanges 3| and 21 being substantially coextensive. A number of holes 32 are provided on said cover 28 for passage of the studs 22, said holes registering with the holes drilled in the bosses 2|. Around said holes there are provided embossinents 33 partially surrounding said stud holes and stiffening the edges of the cover 28 around said holes.

For securing the cover 28 to the plate H at the spark plug nests, there is provided on said cover 28 a converging nipple-shaped flange 34 adapted to fit in the counterbore 26 provided in the spark plug boss 23. A circular groove 35 is provided on the 'bottom of said counterbore, which groove is adapted to receive the edge of the nipple flange 34. The respective heights of the nipple flange 34 and the flange 38 of said cover are so selected that when the nipple flange 34 is fitted in the counterbore 26 a certain amount of pressure is required to bring the flanges 3| and 21 together. The flanges 21 and 3| are positively connected together, preferably by means of a rotary wheel as illustrated in Fig. 3. When said flanges are so connected the nipple flange 34 exerts a resilient and continuous pressure on the bottom of the counterbore 26. The groove 35 is fllled with suitable sealing material, such as liquid Bakelite or other resinous composition of like nature, the same being done before the cover and the plate are assembled together. The tapering surface of said counterbore is also coated with a layer of sealing material and because of the downward pressure of the nipple flange in the process of assembly, the plastic material fllls the entire clearance space between the surfaces of the counterbore 26 and the nipple flange 34.

By virtue of the above construction the top of the cover 28 exerts, when the cylinder head is assembled, continuous yielding pressure on the boss 23 and, therefore, operative vibrations of the cover are absorbed thereby and within certain limits do not affect the tightness of the joint. Because of the provision of the groove 35, a shoulder 36 is formed on the bottom of the counterbore and the same serves as a stop for the edges of the nipple flange 34 as the same tend to move downward and inward in the counterbore because of the straining of the cover by bringing the flanges 3| into contact with the flanges 21.

In accordance with the invention there is provided a method of fabricating the above described cylinder head. The method comprises the steps of providing the cast aluminum base plate H with the flange 21 cast into the material thereof. The bosses 2| and 23 may be provided with holes in the process of casting, or the same may be drilled afterwards. The counterbore in the spark plug boss 23 is next machined. The groove 35 is filled with the liquid "Bakelite and the cover and the base plate are assembled together, the flanges 21 and 3| being brought into contact by any suitable means, such as by clampingthem in several places. The welding rolls 31 are applied to the flanges 21 and 3| and a continuous rotary weld is provided around the entire cylinder head,

I claim:

1. A fluid 'tight joint for an engine cylinder head comprising a bulk metal section having a tapered bore, an annular shoulder on the bottom of said bore, a metal sheet, a conical nipple flange on said sheet fitting into said bore, said sheet being secured to said metal section and adapted to exert resilient pressure on said bore, said nipple flange being engageable with said shoulder when the flange tends to move in a given direction, and a layer of plastic sealing material between said bore and said flange.

2. A fluid tight joint for a cylinder head comprising a bulk metal section having an inwardly converging bore, a metal sheet, a tapering nipple flange on said sheet entering said bore, said sheet being secured to said metal section and adapted to exert continuous pressure on said bore, and means upstanding from the bottom of said bore providing a stop for the edge of said tapering nipple flange in the inward and upward movements thereof.

3. A fluid tight joint for a cylinder head comprising a bulk metal section having an inwardly converging bore and a tapped hole through said section located within the bore, a metal sheet, a tapering nipple flange on said sheet entering said bore, said sheet being secured to said metal section and adapted to exert continuous pressure on said bore, and a shoulder on the bottom of said bore defining said tapped hole for engaging the edge of said nipple flange when the same tends to move inwardly and upwardly of the bore.

4. In a cylinder head made of a base plate and a pressed sheet cover, a water tight joint comprising a boss formed on said plate, said boss being provided with a converging counterbore and a tapped hole located in the counter bore, a converging nipple flange formed on said cover and. adapted to enter and to fit substantially into said bore, said cover being secured to said plate and adapted to exert in assembled position resilient pressure on said bore, a layer of plastic sealing material between said bore and said nipple flange, and a shoulder on the bottom of said bore defining said tapped hole for engaging the edge of said nipple flange.

5. In a composite cylinder head, a cast aluminum base plate, a pressed steel flange cast into the material of said plate and extending around said plate and outwardly therefrom, a pressed steel cover, an outwardly extending flange formed on said cover, said cover flange being coextensive with said plate flange and connected thereto,

said cover being so constructed that it requires pressure to bring said flanges together for welding, a water tight spark plug nest in said cover, said nest comprising a boss formed on said plate, said boss being provided with a converging counterbore, a converging nipple flange formed on said cover and adapted to enter and to flt substantially into said counterbore, said cover being secured to said plate and adapted to exert in assembled position yielding pressure on said counterbore, and a layer of sealing material between said bore and said nipple flange.

6. In a composite cylinder head, a cast aluminum base plate, a pressed steel flange cast into the material of said plate and extending around said plate and outwardly therefrom, a pressed steel cover, an outwardly extending flange formed on said cover, said cover flange being coextensive with said plate flange and connected thereto, said cover being so constructed that it requires pressure to bring said flanges together for welding, a water tight spark plug nest in said cover, said nest comprising a boss formed on said plate, said boss being provided with a converging counterbore, a converging nipple flange formed on said cover and adapted to enter and to flt substantially into said counterbore, said cover being secured to said plate and adapted to exert in assembled position yielding pressure on said counterbore, a layer of sealing material between said bore and said nipple flange, and a shoulder on the bottom of said counterbore for engaging the edge of said nipple flange.

7. A fluid tight joint comprising a bulk metal section having a bore and a tapped hole through said section located within the bore, a metal sheet, a tapering nipple flange on said sheet entering said bore, said sheet being secured to said metal section and adapted to exert continuous pressure on said bore, and a ring-like shoulder on the bottom of said bore surrounding and adjacent said tapped hole for engaging the edge of said nipple flange when the same tends to move inwardly and upwardly of the bore.

8. A fluid tight joint comprising a bulk metal section having an inwardly converging bore and a tapped hole located within the bore, a metal sheet, a tapering nipple flange on said sheet entering said bore, said sheet being secured to said metal section and adapted to exert continuous pressure on said bore, a shoulder on the bottom of said bore defining said tapped hole for engaging the edge of said nipple flange when the same tends to move inwardly and upwardly of the bore, and a layer of plastic sealing material between said bore and said flange.

JOHN TJAARDA. 

